Solid surface modification method and apparatus

ABSTRACT

A liquid compound or a compound solution is kept in contact with the surface of a solid material, such as a synthetic resin, glass, metal, or ceramic, radiation selected from ultraviolet radiation, visible radiation, and infrared radiation is irradiated on the interface between the surface of the solid material and the liquid compound or compound solution to optically excite the surface of the solid material and the liquid compound or compound solution, thereby effecting substitution with a chemical species in the liquid compound or compound solution, depositing the chemical species, or performing etching with the chemical species. Preferably, a transparent window is kept in tight contact with the surface of a solid material to be treated, a thin layer of a liquid compound or of a compound solution is interposed between the surface of the solid material and the transparent window by using capillarity, and ultraviolet radiation, visible radiation, or infrared radiation is irradiated through the transparent window. With this treatment, the irradiated portion can be imparted with hydrophilicity, adhesion properties printing properties, a corrosion resistance, and conductivity.

This is a Continuation of application Ser. No. 08/343,575, filed Feb.17, 1995 now abandon, which is a 371 PCT/JP94/00463 filed Mar. 23, 1994.

TECHNICAL FIELD

The present invention relates to a method of photochemically modifyingthe surface of a solid workpiece to be surface-treated, e.g., formed ofa synthetic resin, glass, a metal, an animal or a plant, or a ceramic,by bringing a liquid compound in or a compound solution into contactwith the surface of the solid workpiece preferably by using a capillaryphenomenon, and irradiating the sample with light in this state. Thepresent invention also relates to an adhesion method and a markingmethod using this surface modification method, and an apparatus forcarrying out these methods.

BACKGROUND ART

There are known a method in which for the purpose of modifying thesurface of a fluoroplastic, which is difficult to adhere because of itssmall affinity for other substances, a fluoroplastic is immersed in atreatment solution comprising liquid ammonia or naphthalene containingmetal sodium and tetrahydrofuran to modify the surface, as well as amethod of chemically modifying the surface of a polyethylene orpolypropylene resin, which is chemically inactive and thereforedifficult to directly print or adhere, by dipping into a mixed solutionof potassium dichromate with concentrated sulfuric acid.

Unfortunately, these conventional chemical modification methods haveproblems in that, in the case of a fluoroplastic, for example, thesurface of a fluoroplastic material turns brown to make the surfacelayer brittle, resulting in peeling of the adhesive layer. Consequently,no satisfactory adhesive strength can be obtained. In addition, althoughthe above conventional methods can modify an entire portion which isimmersed, they cannot perform partial modification unless a photoresistis used as a mask. Also, the treatment reaction is difficult to control,and dangerous chemicals must be used.

There are some other known methods, such as sputtering, coronadischarge, and plasma processing, by which the surface of afluoroplastic or the like is physically modified. However, because ofthe lack of chemical affinity for an adhesive, a roughened surfaceformed acts as a stress concentration point, bringing about bondingbreakdown. This makes it impossible to obtain a high bonding strength.

A polymeric porous membrane or film made from a fluoroplastic, such aspolytetrafluoroethylene (PTFE) or polyvinylidene fluoride, or from apolyethylene or polypropylene resin is being used as a filteringmembrane in precision filtration and ultrafiltration of liquids such aschemicals, foods, and water. Several methods are known as a means forimparting hydrophilicity to these porous membranes in order to improvethe rate of permeation of liquids. Examples are a method of coating asurface active agent, and a method as described in Jpn. Pat. Appln.KOKAI Publication No. 56-63772, in which pores of a porous body areimpregnated with a water-soluble polymer, such as polyvinyl alcohol orpolyethylene glycol, and hydrophilicity is imparted to the porous bodyby, e.g., a heat treatment, acetal conversion, esterification, adichromic acid treatment, or irradiation of ionizing radiation. There isanother known method by which the surface of a fluoroplastic is modifiedby giving hydrophilicity to the surface by irradiation of an ArF laser,as disclosed in Jpn. Pat. Appln. KOKOKU Publication No. 5-77692.

In the method of coating a surfactant, however, the surfactant isreadily removed since it does not strongly adhere to a porous body,resulting in difficulty in keeping hydrophilicity.

In the method described in Jpn. Pat. Appln. KOKAI Publication No.56-63772, deterioration by decomposition of a porous body is broughtabout if, for example, irradiation is used, and this significantlydecreases the mechanical strength. In addition, the use of a heattreatment, acetal conversion, or esterification poses a problem of a lowdegree of hydrophilicity, since a portion of the water-soluble polymeris given hydrophobicity.

Also, the method described in Jpn. Pat. Appln. KOKOKU Publication No.5-77692 is a method of modification of a surface layer; i.e., it is notpossible to sufficiently impart hydrophilicity to the bulk of a porousbody.

The present invention has been made in consideration of the abovesituations and has as its object to provide a method in which a liquidwhich is safe at room temperature is brought into contact with thesurface of a workpiece (a material to be modified), and in this statelight such as ultraviolet light is irradiated on the surface of theworkpiece to selectively and effectively substitute the surface with anarbitrary functional group with no damage to the surface at all, therebymodifying the surface of the workpiece. The present invention alsoprovides a treatment apparatus for this method.

Preferably, it is an object of the present invention to provide a methodin which the liquid described above is forced to closely contact, as anextremely thin layer, with the surface of a workpiece by using acapillary phenomenon or the like, and in this state light such asultraviolet light is irradiated on the surface of the workpiece toselectively and effectively substitute the surface with an arbitraryfunctional group with no damage to the surface at all, thereby modifyingthe surface of the workpiece, and to provide a treatment apparatus forthis method.

The use of a liquid as a surface modifier allows a high-density, uniformtreatment, since the density of contact with an object to be treated ishigh compared to a gas. The use of a liquid is also advantageous fromthe standpoint of environment because only an exposed portion isactivated by light such as ultraviolet radiation.

Incidentally, when laser light is incident on a solution of the typediscussed above, bubbles are usually generated by photo-decomposition,and consequently a treatment solution on the interface of an object tobe treated is removed from the interface. Then, an effective chemicalreaction may not take place. Additionally, if the contact angle, with areaction solution of the surface of an object to be treated is large,the area of contact with the liquid surface becomes small. This contactarea is further decreased by generation of bubbles described above.

In the present invention, therefore, the space between the surface ofglass as an entrance window for light such as ultraviolet radiation andthe surface of a workpiece is made very thin. Consequently, a reactionsolution enters this portion to permit formation of a thin liquid filmon the surface of a workpiece regardless of the contact angle of thematerial with the solution. When light such as ultraviolet radiation isirradiated on the surface of the workpiece in this state, not only theliquid but the surface of the workpiece can be sufficiently excitedbecause of a short path in the liquid. This makes effective opticalmodification feasible.

As discussed above, the surface layer of a solid workpiece can bephotochemically, modified effectively by interposing a thin film of areaction solution between the surface of the solid workpiece andtransparent glass by using capillarity, and irradiating light on thesurface of the workpiece in this state.

DISCLOSURE OF INVENTION

That is, the present invention provides a solid surface modificationmethod, wherein a liquid compound or a compound solution is kept incontact with the surface of a solid material to be treated, radiationselected from the group consisting of ultraviolet radiation, visibleradiation, and infrared radiation is irradiated on the interface betweenthe surface of the solid material and the liquid compound or compound insolution to optically excite the surface of the solid material and theliquid compound or compound solution, thereby effecting substitutionwith a chemical species in the liquid compound or compound in solution,depositing the chemical species, or performing etching with the chemicalspecies.

According to one preferable aspect of the present invention, a thinlayer of the liquid compound or compound in solution is brought intocontact with the surface of a solid material to be treated, and in thisstate ultraviolet radiation, visible radiation, or infrared radiation isirradiated on the interface between the surface of the solid materialand the liquid compound or compound in solution. As a preferable meansof forming this thin layer of the liquid compound or of the compound insolution, a transparent window is kept in close proximity with the uppersurface of a solid material to be treated, and the thin layer is made tobe interposed between them by using capillarity. In this state,radiation selected from ultraviolet radiation, visible radiation, andinfrared radiation is irradiated through the transparent window toexcite the surface of the solid material, thereby effecting substitutionwith a chemical species in the liquid compound or compound in solution,performing etching with the chemical species, or depositing the chemicalspecies.

As the transparent window, it is possible to use any ofultraviolet-transmitting glass, rock crystal, synthetic quartz glass,pyrex glass, optical glass, plate glass, sapphire, diamond, TiO₂,IRTRAN, Ge, Si, barium fluoride, magnesium fluoride, calcium carbonate,lithium fluoride, calcium fluoride, a fluoroplastic, an acrylic resin, astyrene resin, and a carbonate resin.

The shape of the transparent window can be any of a plate, a cylinder, asphere, a donut, and a mold. The solid material to be treated can be anyof a plastic, a metal, an animal or a plant, and a ceramic.

As the liquid compound, it is possible to use any of water, pure water,heavy water, an alcohol, petroleums, an aromatic compound, silicone oil,FOMBLIN oil, trichloroethylene, fluorocarbons (fluorocarbon (freon) 113and fluorocarbon (freon) 113a), hydrogen peroxide, HCl, H₂ SO₄, HNO₃,HCOOH, (COOH)₂, CH₃ COOH, NH₃, N₂ H₄, and NH₄ F.

A solvent can be selected from water, pure water, heavy water, ammonia,sulfuric acid, carbon tetrachloride, carbon disulfide, hydrocarbons,halogen compounds, alcohols, phenols, an organic acid and a derivativethereof, nitriles, nitro compounds, amines, sulfur compounds,petroleums, and ethers.

Radiation usable in the present invention can be selected from anexcimer laser, an Ar⁺ laser, Kr⁺ laser, an N₂ laser, a harmonicsultraviolet laser obtained by a nonlinear material, a D₂ lamp, ahigh-pressure mercury lamp, a low-pressure mercury lamp, an Xe lamp, anHg--Xe lamp, a halogen lamp, an excimer lamp, and an ultra-violet lampobtained by an arc, corona, or silent discharge in an atmosphere of air,nitrogen, or some other gas.

If the solid material to be treated is a fluoroplastic material, asolution having an atom, such as B, Al, Ba, Ga, Li, H, or Ti, whosebonding energy to a fluorine atom is larger than 128 kcal/mol, which isthe bonding energy between a carbon atom and a fluorine atom, and afunctional group with affinity for an adhesive, such as one selectedfrom --OH, --Cl, --NO₂, --CN, --NH₂, --COOH, --CO, --OCH₃, --OC₂ H₅,--OC₃ H₇, --OC₄ H₉, --CONH, --CH₃, --C₂ H₅, --CH₂, --SO₃ H, --C₃ H₇,--C₄ H₉, and --C₆ H₅, is brought into contact with the surface of thefluoroplastic material, and in this state ultraviolet radiation in anamount sufficient to liberate fluorine from the fluoroplastic material,i.e., at at least a photoenergy corresponding to the bonding energy of128 kcal/mol is irradiated on the interface between the fluoroplasticmaterial and the solution. Consequently, it is possible to liberatefluorine from the fluoroplastic material and at the same time substitutethe fluorine with this functional group, thereby performing surfacemodification. This surface-modified fluoroplastic material can be easilybonded to a material of the same kind or a different kind via theadhesive.

That is, the present invention provides a method of bonding afluoroplastic material, wherein prior to bonding a fluoroplasticmaterial to a material of the same type or a different type viaadhesion, the fluoroplastic material is brought into contact with asolution containing a compound having an atom with a bonding energy to afluorine atom of 128 kcal/mol or more and one of a hydrophilic group, alipophilic group, and a functional group inherent in an adhesive, and inthis state ultraviolet radiation in an amount sufficient to liberatefluorine from the fluoroplastic material is irradiated on the interfacebetween the fluoroplastic material and the solution, with a total energyof not less than 128 kcal/mol being delivered by the photons, therebyperforming surface modification in which the fluoroplastic material isdefluorinated and substitution is done by the functional group havingaffinity for the adhesive.

In addition, the present invention provides a method of manufacturing afluoroplastic composite material, wherein fluoroplastic materialssubjected to surface modification by the method described above, or sucha surface-modified fluoroplastic material and a resin material of adifferent kind, are bonded by pressure with an organic solvent in whichthe materials are soluble.

Furthermore, the present invention provides a method of marking afluoroplastic material, wherein an ink or paint containing a compoundhaving an atom with a bonding energy to a fluorine atom of 128 kcal/molor more and one of a hydrophilic group, a lipophilic group, and afunctional group inherent in an adhesive is coated on a fluoroplasticmaterial, and ultraviolet radiation is irradiated on the interfacebetween them, with a total energy of not less than 128 kcal/mol beingdelivered by the photons.

In the present invention, fluoroplastics include a resin made from apolymer or a copolymer of monomers, which contains fluorine atoms, and aresin containing this resin as a base material. Examples arepolytetrafluoroethylene, polychlorotrifluoroethylene,tetrafluoroethylene-hexafluoropropylene, and polyvinylidenefluoride.

Examples of the compound having an atom with a bonding energy to afluorine atom of 128 kcal/mol or more are a boron compound, an aluminumcompound, a barium compound, a gallium compound, a lithium compound, ahydrogen compound, and a titanium compound. Practical examples of thecompound are (BHNH)₃, LiBH₄, NaBH₄, KBH₄, CsBH₄, H₃ BO₃, B(CH₃)₃, B(C₂H₅)₃, B(C₃ H₇)₃, B(C₄ H₉)₃, B(C₆ H₅)₃, B(OH)₂ (C₆ H₅), NaB(C₆ H₅)₄,B(CH₃ O)₃, B(C₂ H₅ O)₃, B(C₄ H₉ O)₃, (NH₄)₂ B₄ O₇, Al(OH)₃, Al(NO₃)₃,AlCl₃, AlBr₃, AlI₃, Al₂ (SO₄)₃, Al(CH₃ COO)₂ OH, Al₂ BaO₄, NH₄ AlCl₄,LiAlH₄, ALNa(SO₄)₂, AlK(SO₄)₂, Al(NH₄)SO₄, Al(CH₃)₃, Al(C₃ H₇)₃, Al(C₂H₅)₃, Al(C₆ H₅)₃, Al(C₂ H₅ O)₃, Al(C₃ H₇ O)₃, Al(C₄ H₉ O)₃, Ba(ClO₄)₂,BaBr, BaI₂, Ba(OH)₂, BaS₂ O₃, Ba(NO₂)₂, Ba(CN)₂, GaCl₃, GaBr, Ga(OH)₃,Ga(SO₄)₃, Ga(NO₃)₃, Ga(CH₃ COO)₃, GaK(SO₄)₂, Ga(CH₃)₃, Ga(C₂ H₅)₃, Ga(C₃H₇)₃, Ga(C₄ H₉)₃, Ga(C₆ H₅)₃, LiCl, LiBr, LiI, LiOH, LiSH, LiN, LiNO₃,Li(CH₃), Li(hydrocarbon compound), Li(C₆ H₅), LiCH₃ O, LiAlH[OC(CH₃)₃]₃, LiNH₂, H₂ O, D₂ O, H₂ O₂, HCOOH, CH₃ COOH, HCl, HNO₃, H₂ SO₄, C₆ H₆,C₆ H₅ CH₃, Ti(CH₂ C₆ H₅)₄, [Ti(C₆ H₅)₂ ]₂, TiCl₃, TiBr4, and TiI4.

Examples of the functional group with affinity for an adhesive are --OH,--Cl, --NO₂, --CN, --NH₂, --COOH, --CO, --OCH₃, --OC₂ H₅, --OC₃ H₇,--OC₄ H₉, --CONH, --CH₃, --C₂ H₅, --CH₂, --SO₃ H, --C₃ H₇, --C₄ H₉, and--C₆ H₅.

If a boron compound, an aluminum compound, a barium compound, a galliumcompound, or a lithium compound is a liquid at room temperature, it isonly necessary to irradiate ultraviolet radiation in an amountsufficient to liberate fluorine from the fluoroplastic material onto theinterface with a workpiece in the liquid. If the compound is in a solidor powder form, the compound is dissolved in a solvent such as water,heavy water, ammonia, sulfuric acid, carbon tetrachloride, carbondisulfide, hydrocarbons, halogen compounds, alcohols, phenols, anorganic acid or its derivative thereof, nitriles, nitro compounds,amines, or sulfur compounds, and ultraviolet radiation in an amountsufficient to liberate fluorine from the fluoroplastic material isirradiated onto the interface with a workpiece in the resultantsolution, with a total energy of not less than 128 kcal/mol beingdelivered by the photons.

Examples of ultraviolet radiation which can provide a photoenergysufficient to liberate fluorine from the fluoroplastic material are anArF excimer laser, an Hg lamp, and an Hg--Xe lamp. An ArF excimer lasercan be shaped into a linear beam by a cylindrical lens and irradiatedalong the interface between a fluoroplastic material being continuouslypulled up from the solution and the solution. It is also possible toirradiate an ArF excimer laser via a pattern corresponding to a bondingportion of a fluoroplastic material. Ultraviolet radiation can also beone from an ultraviolet lamp obtained by an arc, corona, or silentdischarge in an atmosphere of air, nitrogen, or some other gas.

A solution containing a compound having an atom with a bonding energy toa fluorine atom of 128 kcal/mol or more and one of a hydrophilic group,a lipophilic group, and a functional group inherent in the adhesive canbe mixed in the adhesive in advance. In addition, it is also possible tocoat the resultant mixture on the surface of the fluoroplastic material,and to irradiate ultraviolet radiation in an amount sufficient toliberate fluorine from the fluoroplastic material on the interface ofthe coating layer to form an adhesive layer on the surface of thefluoroplastic material, with a total energy of not less than 128kcal/mol being delivered by the photons. Furthermore, a porous materialcan be impregnated with a solution containing a compound having an atomwith a bonding energy to a fluorine atom of 128 kcal/mol or more and oneof a hydrophilic group, a lipophilic group, and a functional groupinherent in the adhesive. In this case, the resultant porous material iskept in tight contact with the fluoroplastic material, and in this stateultraviolet radiation with a photon energy of 128 kcal or more isirradiated on the interface between them.

According to the present invention as discussed above, fluorine isliberated or extracted from the surface of a fluoroplastic material, andthis fluorine is replaced by a functional group with affinity for anadhesive. As a result, the affinity of the surface of the fluoroplasticmaterial for the adhesive is improved to achieve a high adhesivestrength.

If a solid material to be treated is a plastic material having a C--Hbond, a liquid of a compound containing an atom, e.g., B, P, S, Pt, Br,O, Cl, H, or F, whose bonding energy to a hydrogen atom is larger than80.6 kcal/mol, which is the bonding energy between a carbon atom and ahydrogen atom, a functional group (atomic group), such as --OH, --NO₂,--CN, --NH₂, --COOH, --CO, --OCH₃, --OC₂ H₅, --OC₃ H₇, --OC₄ H₉, --CONH,--CH₃, --C₂ H₅, --CH₂, --SO₃ H, --C₃ H₇, --C₄ H₉, or --C₆ H₅, or a metalatom, is brought into contact with the surface of the plastic materialhaving a C--H bond or with a porous body. Surface modification can beperformed in this state by irradiating ultraviolet radiation in anamount sufficient to liberate hydrogen from the plastic material havingC--H bond onto the interface between the surface of the plastic materialand the compound having both the atom and the atomic group or metal atomdescribed above, or a mixture of the compound.

That is, the present invention provides a method of modifying a plasticmaterial having a C--H bond with excitation light, wherein a liquid of acompound or of a mixture, which contains a first atom with a bondingenergy to a hydrogen atom of 80.6 kcal/mol or more and a second atom oratomic group whose bonding energy to the first atom is smaller than theoptical energy of the excitation light, is brought into contact with theplastic material, and in this state ultraviolet radiation in an amountsufficient to liberate hydrogen from the plastic material having C--Hbond is directly or indirectly irradiated on the interface between theplastic material and the compound or mixture, with a total energy of notless than 80.6 kcal/mol being delivered by the photons, therebyliberating or extracting hydrogen from the plastic material via thefirst atom and at the same time substituting the hydrogen with thesecond atom or atomic group.

The compound containing the second atom or atomic group whose bondingenergy to the first atom is smaller than the optical energy of theexcitation light is a liquid containing a compound selected from a boroncompound, a phosphorus compound, a sulfur compound, a platinum compound,a bromine compound, an oxygen compound, a chlorine compound, a hydrogencompound, and a fluorine compound.

Practical examples of the compound are (BHNH)₃, B(CH₃)₃, B(C₂ H₅)₃, B(C₆H₅)₃, B(OH)₂ (C₆ H₅), P(CN)₃, P₂ Se₅, P(CH₃)₃, P(C₂ H₅)₃, P(C₃ H₇)₃,P(C₄ H₉)₃, P(C₆ H₅)₃, P(CH₃)₂ (C₆ H₅), P(CH₃)(C₆ H₅)₂, P(C₆ H₁₇)₃, P(C₆H₁₃)₃, P(C₈ H₁₇)₃, P(CH₃ C₆ H₄)₃, (SCN)₂, SO₂ (NH₂)₂, Pt(CN)₂, Pt(SO₄)₂,BrCN, Br₂ O, Br₂ CF₂, BrCF₃, NO, NO₂, H₂ O₂, O₃, Cl₂ O, ClCN, AgCl,AlCl₃, ASCl₃, AuCl, AuCl₃, BaCl₂, BeCl₂, BiCl₃, CaCl₂, CdCl₂, CeCl₃,CoCl₂, CrCl₂, CsCl, CuCl, CuCl₂, ErCl₃, EuCl₂, EuCl₃, FeCl_(n), GaCl₃,GdCl₃, GeCl₄, H₃ BO₃, Na₂ [Pt(OH)₆ ], K₂ [Pr(OH₆)], O₂, CClF₃, CCl₂ F₂,pure water, heavy water, (COOH)₂, CF₄, CHF₃, HgCl₂, HoCl₃, InCl, IrCl₄,KCl, LiCl, LuCl₃, MgCl₂, MnCl₂, MoCl_(n), NCl₃, NH₄ Cl, NaCl, NbCl5,NiCl₂, PCl₃, PbCl₂, PtCl_(n), RbCl, ReCl₃, SCl_(n), SbCl₃, SeCl_(n),SiCl₄, SnCl_(n), SrCl₂, TaCl₂, TbCl₃, TeCl_(n), ThCl₄, TiCl₃, TICl₃,TmCl₃, UCl_(n), VCl_(n), WCl₆, YCl₃, ZnCl₂, ZrCl₄, H₂ O, NH₃, HCOOH, NH₃OH, H₂ SO₄, HCl, HNO₃, HCF₃, alcohols, hydrocarbons, aromatics, AgF,ASF₃, BaF₂, BeF₂, BiF₃, CdF₂, CeF₃, CoF₂, CsF, CuF, GeF₂, KF, MoF_(n),NH₄ F, NaF, NbF₅, NiF, UF₆, VF_(n), ZnF₂, and CF₄.

Examples of the atomic group are --OH, --NO₂, --CN, --NH₂, --COOH, --CO,--OCH₃, --OC₂ H₅, --OC₃ H₇, --OC₄ H₉, --CONH, --CH₃, --C₂ H₅, --CH₂,--SO₃ H, --C₃ H₇, --C₄ H₉, and --C₆ H₅.

The above compound can be dissolved in a solvent such as water, purewater, heavy water, ammonia, sulfuric acid, carbon tetrachloride, carbondisulfide, hydrocarbons, halogen compounds, alcohols, phenols, organicacids and derivatives thereof, nitriles, nitro compounds, amines, orsulfur compounds.

The ultraviolet radiation in an amount sufficient to liberate hydrogenfrom the compound having C--H bond may be obtained from a radiationsource which can be provided from one or a combination of excimerlasers, such as XeF, XeCl, KrF, and ArF lasers, an N₂ laser, a Kr ionlaser, an Ar ion laser, and harmonics laser light by a nonlinearelement, one or a combination of an Hg lamp, an He--Xe lamp, a D₂ lamp,and an excimer lamp, or one or a combination of ultraviolet radiationsobtained by an arc, corona, or silent discharge in an atmosphere of air,nitrogen, or some other gas.

If the bonding energy of a side chain, except for a C--H bond, whichconstitutes a plastic material, is smaller than a photon energy ofexcitation light for optically decomposing the compound, ultravioletradiation in an amount sufficient to liberate hydrogen from the compoundhaving C--H bond and smaller than the bonding energy of a side chainexcept for the C--H bond can be directly irradiated on the plasticmaterial, and another ultraviolet radiation with a photon energy largerthan the bonding energy of the compound can be irradiated on thecompound so as not to directly illuminate the plastic material (it can,for example, be irradiated parallel to the surface of the plasticmaterial).

In this case, it is possible to use an XeF, XeCl, or KrF laser asultraviolet radiation to be directly irradiated on the plastic materialhaving the C--H bond, and an XeCl, KrF, or ArF laser as ultravioletradiation to be indirectly incident parallel to the surface of theplastic material.

In addition, an Hg or Hg--Xe lamp light with a wavelength of 300 nm ormore can be used as ultraviolet radiation to be directly irradiated onthe plastic material having the C--H bond, and an Hg, Hg--Xe, D₂, orexcimer lamp with a wavelength of 300 nm or more can be used asultraviolet radiation to be indirectly incident parallel to the surfaceof the plastic material.

As described above, hydrogen atoms on the surface of a plastic materialmust be liberated from the surface of the plastic material before beingsubstituted with the atomic group or the metal atom. Since the energy ofthis C--H bond is 80.6 kcal/mol, it is necessary to break the bond byirradiating an optical energy larger than this energy. To preventrecombination of H and C atoms, however, an atom with a bonding energylarger than that of the C atom must be present near the H atom.

A coparison of bonding energies is presented below. In this comparison,each number is expressed in kcal/mol. ##EQU1##

The larger the bonding energy, the larger the power of dehydrogenation.Examples of a compound of an atom capable of dehydrogenation are shownin claim 2. Although dehydrogenation is possible by B, P, S, Pt, or Brwhose bonding energy is relatively low, O, Cl, H, and F are practical.Of these atoms, H and F atoms have the strongest dehydrogenation power.To be precise, it is desirable that the photon energy to be irradiatedbe smaller than the bonding energy of a molecule bonded to hydrogen.

A liquid of a compound or of a mixture, which contains the atom and theatomic group (functional group) for dehydrogenation, or a compounddissolved in a solvent, is brought into contact with a plastic materialhaving a C--H bond, and ultraviolet radiation with energy required tobreak the C--H bond and the bond of the dehydrogenation atom of thecompound is irradiated on the interface between them. Consequently,dehydrogenation and substitution reactions occur simultaneously,modifying the surface of the plastic material.

If the bonding energy for decomposing the compound is larger than theenergy of the C--H bond, ultraviolet radiation with a high photon energyis irradiated parallel to the surface of a plastic material, and at thesame time ultraviolet radiation in an amount sufficient to liberatehydrogen from the plastic material having C--H bond is irradiatedperpendicularly to the plastic material, in order to decompose only thecompound in the vicinity of the plastic material. This allows moreeffective modification.

In the present invention as discussed above, hydrogen is liberated fromthe surface of a plastic material having a C--H bond, and this hydrogenis substituted with various types of functional groups or metal atoms.As a result, the surface of the plastic material acquires wettability,printing properties, adhesion properties, corrosion resistance,conductivity, and conductor characteristics.

If a solid material to be treated is a porous film, e.g., afluoroplastic porous film, pores of the fluoroplastic porous film areimpregnated with a compound having an atom with a bonding energy to afluorine atom of 128 kcal/mol or more and a hydrophilic group or alipophilic group. In this state radiation in an amount sufficient toliberate fluorine from the fluoroplastic porous film can be irradiatedto modify the fluoroplastic porous film, with a total energy of not lessthan 128 kcal/mol being delivered by the photons.

By irradiating radiation in such an amount in this fashion, the C--Fbond (128 kcal/mol) of the fluoroplastic is broken. In this case, byallowing an atom with energy higher than the C--F bonding energy toexist, the fluorine atom thus broken is bonded to the atom and trapped.Since a fluorine atom has a large electronegativity of 4.0,recombination of C and F can be prevented by making an atom with anelectronegativity smaller than that of a carbon atom (electronegativity:2.5) exist. Also, the bond between this atom and a fluorine atom isdifficult to break again, since the bonding energy of this bond ishigher than that of the C--F bond (128 kcal/mol). Therefore, somefluorine atoms of the fluoroplastic can be substituted with ahydrophilic functional group.

The radiation in this case can be selected from the group consisting ofan excimer laser, an Ar⁺ laser, a Kr⁺ laser, an N₂ laser, a harmonicsultraviolet laser obtained by a nonlinear material, a D₂ lamp, ahigh-pressure mercury lamp, a low-pressure mercury lamp, an Xe lamp, anHg--Xe lamp, a halogen lamp, an excimer lamp, and an ultraviolet lampobtained by an arc, corona, or silent discharge in an atmosphere of air,nitrogen, or some other gas.

The compound described above can be selected from the group consistingof a boron compound, an aluminum compound, a hydrogen compound, a bariumcompound, a gallium compound, a lithium compound, and a titaniumcompound.

The porous body for use in the present invention is not particularlylimited. In the case of a fluoroplastic porous body, examples other thanPTFE are a tetrafluoroethylene-hexafluoropropylene copolymer, anethylene-tetrafluoroethylene copolymer, atetrafluoroethylene-perfluoroalkylvinylether copolymer, a vinyl fluorideresin, a vinylidene fluoride resin, and an ethylene chloride trifluorideresin.

This porous body can take any given shape, such as a sheet or a tube,and can be either a calcined or non-calcined product. The porosity andnominal pore size of the porous body can be freely set in accordancewith the intended use. However, it is usually preferable that theporosity be 20 to 80% and the nominal pore size be about 0.01 to 10 μm.

A compound to be used in this case as a modification medium can be anyof those enumerated above. These compounds can be used in the form of anaqueous solution and can be added with an alkali salt, such as sodiumhydroxide or potassium hydroxide, in order to increase the solubility ofthe solute.

As a method of impregnating a porous body with the compound, any givensimple method such as impregnation or coating can be employed. A porousbody can also be subjected to ultrasonic cleaning in advance by dippingin an organic solvent.

As an example, various methods can be used in impregnating pores of afluoroplastic porous body with the aqueous compound solution. It is,however, preferable to employ the following methods when thehydrophobicity of this porous body is taken into account.

(1) A method of performing impregnation through:

(a) the first step of dipping a fluoroplastic porous body into anorganic solvent (e.g., methanol, ethanol, acetone, ether, orisopropylalcohol) having a high compatibility with water and a surfacetension of 30 dyne/cm or less, thereby impregnating the porous body withthe solvent;

(b) the second step of dipping the resultant porous body in water toreplace the solvent with water (impregnate pores with water); and

(c) the third step of dipping the porous body in an aqueous compoundsolution to replace water with the aqueous solution (impregnate poreswith the aqueous solution).

(2) A method in which a compound is mixed in a low-surface-tensionorganic solvent as described above to prepare a solvent with a surfacetension of 30 dyne/cm or less, and the resultant solvent is coated orsprayed on a fluoroplastic porous body, or the fluoroplastic porous bodyis dipped in the solvent, thereby impregnating pores of thefluoroplastic porous body with the aqueous compound solution.

With this method, it is possible to easily obtain a hydrophilicfluoroplastic porous film having a high hydrophilicity and improved indurability, chemical resistance, solvent resistance, and heatresistance, without performing any vacuum operation such as a dischargeprocess.

As an apparatus using capillarity mentioned above, the present inventionprovides a solid surface modification apparatus comprising a table forplacing a solid material to be treated, a plate-like transparent windowcapable of being placed on the upper surface of the solid materialplaced on the table, illuminating means for irradiating ultravioletradiation, visible radiation, or infrared radiation substantiallyperpendicularly on the upper surface of the solid material placed on thetable, wherein a thin layer of a liquid compound or of a compoundsolution is interposed between the solid material and the plate-liketransparent window by using capillarity, and in this state light isirradiated from the illuminating means onto the upper surface of thesolid material to modify the solid surface.

This illuminating means can be so arranged as to selectively irradiatethe upper surface of the solid material to be treated with ultravioletradiation, visible radiation, or infrared radiation.

As an apparatus using a capillary phenomenon, the present invention alsoprovides a solid surface modification apparatus comprising a rotatablerubber roller, a cylindrical transparent round rod or transparent pipecapable of rotating and placed parallel to the rubber roller, means forpassing a sheet-like solid material to be treated between the rubberroller and the cylindrical transparent round rod or transparent pipe,illuminating means for linearly irradiating ultraviolet radiation,visible radiation, or infrared radiation to a position at which therubber roller and the cylindrical transparent round rod or transparentpipe oppose each other, and means for urging the rubber roller and thecylindrical transparent round rod or transparent pipe against each othervia the sheet-like solid material, wherein a thin layer of a liquidcompound or of a compound solution is interposed between the sheet-likesolid material and the cylindrical transparent round rod or transparentpipe by using capillarity, and in this state light is irradiated fromthe illuminating means onto the upper surface of the solid material tocontinuously modify the solid surface.

This illuminating means can be arranged outside the cylindricaltransparent round rod or transparent pipe. Alternatively, theilluminating means can consist of a reflecting mirror arranged insidethe transparent pipe and means for emitting a linear beam from an endportion of the pipe, or can be an elongated lamp inserted inside thetransparent pipe. That is, the illuminating means can be properly chosenfrom these structures.

As an apparatus using capillarity, the present invention furtherprovides a method of modifying the surface of a lens, wherein a lens tobe subjected to a surface treatment is sandwiched between a concave lensand a convex lens, thin layers of a compound solution are interposedbetween the lens to be treated (e.g., a contact lens) and the concavelens and between the lens to be treated and the convex lens bycapillarity, and in this state light is irradiated on both the surfacesof the lens to treat and modify the surfaces.

In addition, the present invention provides a method in which atransparent liquid plastic (e.g., silicon rubber, fluoroplastic, orPMMA) is flowed on the surface of a solid material to be treated, whichassumes a complicated shape, to form a mold, and the mold is hardenedand released. Thereafter, a thin layer of a compound solution isinterposed between this mold and the surface of the solid material to betreated (e.g., a denture) by using capillarity, and light is irradiatedfrom the mold side onto the surface of the solid material, therebymodifying the surface.

Furthermore, the present invention provides an apparatus in which awindow is formed into a donut-like shape, and a thin liquid film layeris interposed between the surface of a solid material to be treated(e.g., a sheath of an electric wire or a jacket of a tube), whichcorresponds to the inner circumferential surface of the donut-likewindow, and the inner circumferential surface of the window by using acapillary phenomenon. In this apparatus, the surface of the solidmaterial whose outer circumference is a circle can be continuouslymodified by irradiating light on the surface from the outercircumferential surface of the window. By arranging a plurality of theseapparatuses, more effective surface modification can be performed.

Moreover, it is found that when water, an oil, or an adhesive isinterposed between fluoroplastic sheets or between a fluoroplastic sheetand a material to be adhered, and ArF excimer laser light is irradiatedthrough the fluoroplastic sheet while closely adhering these materialsby pressure, these fluoroplastic sheets or the fluoroplastic sheet andthe material to be adhered are strongly chemically adhered to each otheraccording to the present invention. The reason for this is assumed to bethat hydrogen atoms optically dissociated from water (H₂ O) or oilliberate fluorine atoms from the surface of the fluoroplastic sheet,oxygen atoms dissociated from water or oil are substituted to thepositions from which the fluorine atoms are released, and consequentlynonbonded hands on the surface of the fluoroplastic sheet have the sameoxygen atom in common to give a strong adhesive force.

This similarly applies to an adhesive; that is, it is assumed thathydrogen atoms optically dissociated from an adhesive liberate fluorineatoms from the surface of a fluoroplastic sheet which is simultaneouslyexcited, and nonbonded hands of the adhesive which has lost hydrogenatoms are bonded to the positions from which the fluorine atoms arereleased, resulting in a strong adhesion force.

According to the present invention, it is also found that anantithrombotic material required for an artificial blood vessel or organcan be readily formed by the use of a fluoroplastic material.

When coherent light radiated from a single light source such as a laseris split into two optical paths and again made incident at respectivecertain angles, interference takes place at the intersection of theselight components. Generally, a material coated with a sensitizing agentis placed on this interference portion. In the present invention,however, a transparent window is placed on the surface of a solidmaterial to be treated via a compound liquid film, and ultraviolet laserbeams incident through the transparent window from two or moredirections are caused to interfere with each other on the interfacebetween the surface of the solid material and the liquid layer.Consequently, only a portion of the surface of the solid materialcorresponding to the portion of interference is photochemicallymodified.

Especially when two light beams are incident from two directions whiletheir respective Brewster angles are maintained, only p-polarized lightis incident inside the window. This permits high-efficiency modificationin the form of a diffraction grating.

Also, a partial side surface of a window is formed into a plane mirror,and ultraviolet radiation is irradiated obliquely from the side awayfrom the side of the plane mirror such that light directly propagatingthrough the window and light reflected by the internal plane mirrorinterfere with each other. The result is modification in adiffraction-grating form on the surface of the solid material via thewindow and a thin layer of a compound liquid film. Especially when theangle of incidence of ultraviolet laser light to be obliquely incidentis maintained at a Brewster angle, only p-polarized light brings aboutinterference, resulting in a high interference efficiency. When thesurface of a material is modified in the form of a grating, e.g., when ahydrophilic group is substituted in a grating form by using afluoroplastic material as a solid material to be treated, a hydrophilicor hydrophobic micro domain structure is formed. This allows easyformation of an antithrombotic material necessary for an artificialblood vessel or organ by the use of a fluoroplastic material.

As discussed earlier, the angle of contact between a substance to bemodified and a liquid is large. For this reason, the contact area withthe surface of a sample becomes small, and bubbles generated byphoto-decomposition further decrease the contact area. As in the presentinvention, however, by keeping the sample and the glass surface in tightcontact with each other and interposing a compound solution between themby using capillarity, an even thin liquid film can be formed on theentire surface of the sample. When ultra-violet radiation is incidentfrom the side of the glass surface, the liquid is locally, opticallydecomposed, and the surface of the sample is also excited with afraction of light transmitted through the liquid, bringing about achemical reaction. Additionally, since the liquid film is thin, allparts of the decomposition product are consumed in the surfacetreatment, so no excess reaction product which causes generation ofbubbles forms. Consequently, no bubbles are generated, making a highlyefficient surface treatment possible.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view showing an embodiment of an apparatus forexplaining a solid surface modification method according to the presentinvention;

FIG. 2 is a perspective view showing one embodiment of a solid surfacemodification apparatus according to the present invention;

FIG. 3 is a perspective view showing another embodiment of the solidsurface modification apparatus according to the present invention;

FIG. 4 is a side view showing an embodiment of an apparatus formodifying the surface of a contact lens according to the presentinvention;

FIG. 5 is a perspective view showing still another embodiment of thesolid surface modification apparatus according to the present invention;

FIG. 6 is a schematic view showing a fluoroplastic surface treatmentapparatus used to carry out the method of the present invention;

FIG. 7 is a graph showing the characteristics of the surface of afluoroplastic treated by the method of the present invention;

FIG. 8 is a perspective view showing a fluoroplastic surface treatmentapparatus used to carry out the method of the present invention; and

FIG. 9 is a graph showing the characteristics of the surface of afluoroplastic treated by the method of the present invention.

BEST MODE OF CARRYING OUT THE INVENTION

Embodiments of the present invention will be described below withreference to apparatuses illustrated in the drawings.

FIG. 1 shows an embodiment of an apparatus for explaining the method ofthe present invention. In this apparatus, a compound solution 2 isdropped on a material (sample) 1 to be modified (FIG. 1(a)), a syntheticquartz glass plate 3 is placed on the compound solution 2 thus dropped(FIG. 2(b)), and a load is applied. Consequently, a thin even liquidfilm is formed in the gap between the material 1 and the glass plate 3by a capillary phenomenon. By perpendicularly irradiating an ultravioletlaser beam onto the resultant structure from an excimer laser device 4through, e.g., a mask 5 as in FIG. 1(c), only in the exposed portion isthe liquid optically decomposed and the surface of the material 1excited, resulting in a chemical reaction occurring between them. Sincethe liquid film is thin, absorption of the laser beam in the liquid 2can be suppressed. This allows a large proportion of the ultravioletradiation to reach the surface of the material 1. Also, since the liquidfilm is thin, all parts of the decomposition product are used in thesurface treatment. Therefore, almost no excess reaction product isformed, which causes generation of bubbles when an ultraviolet laserbeam is irradiated on a material to be modified that is dipped in asolution in conventional methods. This makes an effective surfacetreatment feasible.

FIG. 2 shows one embodiment of another apparatus for carrying out themethod of the present invention. This apparatus comprises a rotatablerubber roller 11, a cylindrical transparent round rod or transparentpipe 12 capable of rotating and placed parallel to the rubber roller 11,a cylindrical lens 13 arranged above the cylindrical transparent roundrod or transparent pipe 12, an illuminating means (not shown) forlinearly irradiating, via the cylindrical lens 13, ultravioletradiation, visible radiation, or infrared radiation to a position atwhich the rubber roller 11 and the cylindrical transparent round rod ortransparent pipe 12 oppose each other, a means (not shown) for passing asheet-like solid material 14 to be treated through a position betweenthe rubber roller 11 and the cylindrical transparent round rod ortransparent pipe 12 in the direction indicated by an arrow, and anurging means for urging the cylindrical transparent round rod ortransparent pipe 12 against the rubber roller 11.

In this apparatus, a compound in solution 2 as a reaction solution isdropped on the surface of the sheet-like solid material 14 on theupstream side. This compound solution 2 spreads along the lower surfaceof the cylindrical transparent round rod or transparent pipe 12 bycapillarity when the solution reaches the lower surface of thetransparent round rod or pipe 12, thereby forming a thin layer.Therefore, by irradiating light (e.g., an ultraviolet laser beam) fromthe illuminating means onto the upper surface of the solid material 14in this state, the surface of the sheet-like solid material 14 can beefficiently and continuously modified.

FIG. 3 shows a modification of the apparatus illustrated in FIG. 2. Thedifference of this apparatus from that in FIG. 2 is that a reflectingmirror 21 is arranged inside a transparent pipe 12 and an elongated lamp(Hg lamp) 22 is inserted inside the transparent pipe 12. The rest of thearrangement is identical with the apparatus shown in FIG. 2. Therefore,the same reference numerals as in FIG. 2 denote the same parts in FIG.3, and a detailed description thereof will be omitted.

In this apparatus, as in the apparatus in FIG. 2, a compound solution 2as a reaction solution is dropped on the surface of a sheet-like solidmaterial 14 to be treated on the upstream side. This compound solution 2spreads along the lower surface of the transparent pipe 12 by acapillary phenomenon when the solution reaches the lower surface of thepipe 12, thereby forming a thin layer. Therefore, by irradiating light(e.g., an ultraviolet laser beam) from the lamp 22 onto the uppersurface of the solid material 14 in this state, the surface of thesheet-like solid material 14 can be efficiently and continuouslymodified.

When the sheet-like material to be modified is compressed together withthe dropped liquid by a synthetic quartz pipe 11 and a rubber roller, athin straight liquid film is formed in the compressed portion bycapillarity. The surface of the material in this state can becontinuously modified by irradiating a linear beam which is formed byshaping a laser beam through a lens, or by irradiating the linear liquidfilm by using a mercury lamp inserted into the synthetic quartz pipe, asshown in FIG. 3. A more effective surface modification is possible byarranging a plurality of these surface modification apparatuses alongthe sheet-like material to be modified.

FIG. 4 shows a method of modifying the surface of a lens (e.g., acontact lens) in accordance with the method of the present invention. Alens 33 to be treated (whose curvature is identical or nearly identicalwith those of a concave lens 31 and a convex lens 32) which is to besubjected to a surface treatment is placed between the concave lens 31and the convex lens 32. A compound solution 2 is dropped between thelens 33 and the concave lens 31 and between the lens 33 and the convexlens 32, forming thin layers of the compound solution by capillarity. Inthis state light (e.g., an excimer laser beam) is irradiated on both thesurfaces of the lens 33, thereby modifying these surfaces. Consequently,both the surfaces of the lens 33 to be treated can be modified at onetime.

EXAMPLE 1

Modification of a fluoroplastic (FEP) sheet was performed by using theapparatus illustrated in FIG. 1. In this example, pure water and tapwater were used as the compound solution 2. That is, a thin even liquidfilm of each of pure water and tap water was formed between thesynthetic quartz glass plate 3 and a fluoroplastic (FEP) sheet bypressing the glass plate 3. In this state, an ArF laser beam wasirradiated with an energy density of 6.5 mJ/cm². Consequently,hydrophilicity was brought about for both pure water and tap water, withthe result that a contact angle with water of 30° was obtained.

Note that, for comparison, an identical fluoroplastic (FEP) sheet wasdipped in the same solution, and an ultraviolet laser beam wasirradiated to perform surface modification for the fluoroplastic (FEP)sheet. As a result, irradiation of an ArF laser beam with an energydensity of 6.5 mJ/cm² was required to obtain a contact angle with waterof 30° when pure water was used, whereas irradiation of an ArF laserbeam with an energy density of 15 mJ/cm² was necessary when tap waterwas used.

EXAMPLE 2

The apparatus shown in FIG. 1 was used to modify a fluoroplastic (FEP)sheet. In this example, formic acid was used as the compound in solution2. That is, a thin even liquid film of formic acid was formed betweenthe synthetic quartz glass plate 3 and a fluoroplastic (FEP) sheet bypressing the glass plate 3. In this state, an ArF laser beam wasirradiated with an energy density of 25 mJ/cm². Consequently, a contactangle with water of 10° was obtained.

Note that, for comparison, an identical fluoroplastic (FEP) sheet wasdipped in formic acid, and an ultraviolet laser beam was irradiated toperform surface modification for the fluoroplastic (FEP) sheet. However,modification was impossible because bubbles were generated.

EXAMPLE 3

A fluoroplastic (PTFE) sheet was modified by using the apparatusesillustrated in FIGS. 2 and 3. That is, continuous surface modificationwas done by dropping droplets of methylalcohol (CH₃ OH) one by one onthe surface of a fluoroplastic (PTFE) sheet while the fluoroplasticsheet was moved. When an ArF laser beam was irradiated as 3000 shotswith an energy density of 25 mJ/cm², a contact angle with water of 45°and a contact angle with benzene of 15° were obtained. This demonstratesthat the modified surface had both hydrophilic and lipophilic natures.

EXAMPLE 4

The apparatus illustrated in FIG. 4 was used to modify both the surfacesof a PMMA contact lens. First, liquid films of a solution prepared bydissolving 2 g of ammonia borate [(NH₄)₂ B₄ O₇ ] in 50 cc of water wereformed on both the surfaces of a contact lens by using a capillaryphenomenon. In this state, an ArF laser beam was irradiated 1000 shotswith an energy density of 20 mJ/cm² from both the sides of the contactlens. Consequently, a contact angle with water of 10° was obtained,indicating hydrophilicity.

EXAMPLE 5

Surface modification of a silicon wafer was performed by using theapparatus shown in FIG. 1. That is, one droplet of hydrogen peroxide (H₂O₂) was dropped on the surface of a silicon wafer and pressed by thesynthetic quartz glass plate 3, forming a thin even liquid film betweenthe glass plate 3 and the silicon wafer. In this state, an ArF laserbeam was irradiated as 1000 shots with an energy density of 50 mJ/cm².Consequently, SiO₂ was formed only on the exposed surface. A peak ofSiO₂ was found at 99 ev by ESCA.

EXAMPLE 6

Surface modification of aluminum was performed by using the apparatusshown in FIG. 1. That is, one droplet of hydrogen peroxide (H₂ O₂) wasdropped on the surface of aluminum and pressed by the synthetic quartzglass plate 3, forming a thin even liquid film between the glass plate 3and the aluminum. In this state, an ArF laser beam was irradiated as1000 shots with an energy density of 50 mJ/cm². Consequently, Al₂ O₃ wasformed only on the exposed surface. When the surface of the materialthus treated was dipped in an aqueous NaOH solution, the Al₂ O₃ portionwas not corroded.

EXAMPLE 7

An apparatus illustrated in FIG. 5 was used to bond two fluoroplasticsheets (FEP) with pure water or tap water. In FIG. 5, reference numeral43 denotes a synthetic quartz round rod lens constituting a cylindricallens; 44, a roller for urging members to be treated against thesynthetic quartz round rod lens 43; 45 and 46, pressure springs attachedto the two ends of the roller; 41 and 42, fluoroplastic sheets as themembers to be treated; and 47, a rectangular ArF excimer laser beam.

First, one droplet of pure water was dropped between the twofluoroplastic sheets 41 and 42. Continuous bonding was then performed byurging the synthetic quartz round rod lens 43 constituting thecylindrical lens against the roller 44 while moving the sheets 41 and42. When the rectangular ArF excimer laser beam was incident from thecircumferential portion of the synthetic quartz round rod lens 43, alinear beam was obtained on the surface where the round rod lens 43 andthe fluoroplastic sheet 41 were in contact. Note that the laser beam wasincident with an energy density of 50 mJ/cm² and a repetition pulse rateof 3000 shots while the pressure between the two fluoroplastic sheets 41and 42 was held at 10 kgf/cm². The resultant sample was subjected to atensile shear test and found to have an adhesive strength of 30 kgf/cm².

The same test was conducted by using tap water instead of pure water. Asa result, nearly the same adhesive strength as in the case of pure waterwas obtained.

EXAMPLE 8

The apparatus shown in FIG. 5 was used in this example. First, a thinlayer of an epoxy adhesive was coated between a stainless steel plateand a fluoroplastic sheet (FEP). While the synthetic quartz round rodlens 43 was urged against the roller 44, a laser beam with an energydensity of 40 mJ/cm² was irradiated on the interface between thefluoroplastic sheet and the adhesive at a repetition pulse rate of 6000shots. Thereafter, the adhesive was cured at 80° C. for 15 hours, andthe resultant sample was subjected to a tensile shear test.Consequently, the adhesive strength that was 1 kgf/cm² or less beforethe laser beam was irradiated was improved to 84 kgf/cm² afterirradiation of the laser beam.

EXAMPLE 9

The apparatus illustrated in FIG. 5 was used. First, one droplet of acyanol-based instant adhesive (Aron Alpha (tradename)) was droppedbetween an acryl plate and a fluoroplastic sheet (FEP). While thesynthetic quartz round rod lens 43 was urged against the roller 44, alaser beam with an energy density of 30 mJ/cm² was irradiated on theinterface between the fluoroplastic sheet and the adhesive at arepetition pulse rate of 7000 shots. The resultant sample was subjectedto a tensile shear test. Consequently, the adhesive strength that was0.2 kgf/cm² or less before the laser beam was irradiated was improved to25 kgf/cm² after irradiation of the laser beam.

Note that when a slight amount of acetic acid was mixed in thecyanol-based instant adhesive described above, the cure time waslengthened to improve the workability. Since this made repetitive laserirradiation for a long time period possible, the tensile shear strengthwas improved to 40 kgf/cm² after irradiation of 10,000 shots.

EXAMPLE 10

One droplet of water was dropped on a fluoroplastic plate, and a quartzglass plate was kept in tight contact with the fluoroplastic plate.Thereafter, ArF laser beams (energy density 10 mJ/cm², repetition pulserate 3000 shots) split into two optical paths were guided to cross eachother on the interface between the material to be treated and waterthrough a plate synthetic quartz window, while the angle of incidencewith the quartz window was held at 33°. Consequently, it was found frommeasurements made by SEM and EPMA that portions modified to havehydrophilicity were formed at intervals of 2123 Å.

EXAMPLE 11

A side surface of disk-like synthetic quartz glass was ground andpolished, and Al was vapor-deposited only on that surface, therebymaking a window having an internal plane mirror. The resultant windowwas kept in tight contact with the surface of a fluoroplastic sheet(FEP) via water. An ArF laser beam (energy density: 10 mJ/cm²,repetition pulse rate: 3000 shots) was caused to be incident from theside away from the side of the internal plane mirror with an angle of33° held with respect to the window, such that a half of the beam wasreflected by the plane mirror. Consequently, it was found frommeasurements done by SEM and EPMA that there were portions in which thelight reflected by the internal plane mirror of the window and the lightdirectly propagating through the window crossed each other, i.e.,portions modified to have hydrophilicity due to photochemicalsubstitution on the interface between the material and water, atintervals of 2123 Å.

EXAMPLE 12

An apparatus shown in FIG. 6 was used to perform a surface treatment fora fluoroplastic material (polytetrafluoroethylene). In FIG. 6, referencenumeral 51 denotes an excimer laser device; 52, a mask; 53, a mirror; 54and 55, lenses; 56, a reactor vessel; and 57, a fluoroplastic sheet as asample.

To begin with, a solution prepared by dissolving 50 cc of methylalcohol(CH₃ OH) and 5 g of sodium tetrahydroborate (Na[BH₄ ]) was placed in thereactor vessel 56. The fluoroplastic sheet 57 was dipped in thesolution, and an ArF laser beam was irradiated on the interface betweenthe solution and the fluoroplastic sheet 57. As a result, both alipophilic group and a hydrophilic group were found as shown in FIG. 7.That was confirmed from the results of measurements of infraredabsorption spectra using ATR-FTIR; that is, substitution of a methylgroup was confirmed by absorption near 2900 cm⁻¹, and substitution of ahydroxyl group was confirmed by absorption near 3300 cm⁻¹. Also,defluorination was confirmed by X-ray photoelectron spectroscopy (XPS).The fluoroplastic sheet 57 thus treated was bonded to a stainless steelplate with an epoxy resin-based adhesive and subjected to a tensileshear test. The adhesive strength was found to be 140 kgf/cm².

EXAMPLE 13

An apparatus illustrated in FIG. 8 was used to perform a surfacetreatment for a fluoroplastic material (FEP). In FIG. 8, referencenumeral 61 denotes an excimer laser device; 62, a mask; 63, a mirror;64, a lens; 65, a compound liquid; 66, a reactor vessel; 67, afluoroplastic sheet as a sample; and 68, a sponge sheet.

First, 5 g of sodium tetrahydroborate were dissolved in 50 cc of water,and the sponge sheet 68 was soaked with the resultant solution 65. Thisprevents generation of bubbles and removal of the liquid from thefluoroplastic sheet sample 67. Thereafter, the transparent fluoroplastic(FEP) sheet sample 67 was placed on the sponge sheet 68, and an ArFlaser beam (10 mJ/cm²) was irradiated from above. Consequently, as inFIG. 9, the contact angle with water which was 110° before the treatmentwas improved to 10° after that. The resultant surface-modifiedfluoroplastic sheet material was bonded to a stainless steel plate withAron Alpha (tradename), and it was found that the adhesive strength was60 kgf/cm².

EXAMPLE 14

2 g of boric acid (H₃ BO₃) were dissolved in 50 cc of water, a spongesheet was soaked with the resultant solution, and a fluoroplastic (FEP)sheet sample was treated following the same procedures as in Example 13.Consequently, a hydroxyl group (OH) was substituted on the surface ofthe fluoroplastic sheet sample with an ArF laser energy density of 15mJ/cm², resulting in a contact angle with water of 5°. When thissurface-modified fluoroplastic sheet sample was bonded to a stainlesssteel plate with Aron Alpha (tradename), the adhesive strength was foundto be 60 kgf/cm².

EXAMPLE 15

2 g of boric acid (H₃ BO₃) were dissolved in 50 cc of ammonia water, asponge sheet was soaked with the resultant solution, and a transparentfluoroplastic (FEP) sheet sample was treated following the sameprocedures as in Example 13. Consequently, an amino group (--NH₂) wassubstituted on the surface of the fluoroplastic sheet sample to giverise to hydrophilicity. As a result of measurements of infraredabsorption spectra using ATR-FTIR, the substitution of an amino groupwas confirmed by absorption of NH near 3500 cm⁻¹. Also, defluorinationwas confirmed by X-ray photoelectron spectroscopy (XPS). At that time,the ArF laser energy density was 20 mJ/cm², and the contact angle withwater was 5°. This surface-modified fluoroplastic sheet sample wasbonded to a stainless steel plate with an epoxy resin-based adhesive andsubjected to a tensile shear test. The adhesive strength was found to be140 kgf/cm².

EXAMPLE 16

A solution prepared by dissolving 2 g of boric acid (H₃ BO₃) in 50 cc ofmethylalcohol was placed in the reactor vessel 56 shown in FIG. 6. Afluoroplastic sheet sample was dipped in the solution, and a 15-mJ/cm²ArF excimer laser beam was irradiated on the interface between thesolution and the sample. Consequently, the contact angle with benzenewas 10°, indicating a lipophilic nature. This surface-modifiedfluoroplastic sheet sample was bonded to a stainless steel plate with anepoxy resin-based adhesive and subjected to a tensile shear test. Theadhesive strength was found to be 120 kgf/cm².

EXAMPLE 17

A solution prepared by dissolving 2 g of boric acid (H₃ BO₃) in 50 cc oftoluene (C₆ H₆.CH₃) was placed in the reactor vessel 56 illustrated inFIG. 6. Following the same procedures as in Example 12, a fluoroplasticsheet sample was dipped in the solution, and an ArF laser beam wasirradiated on the interface between the solution and the sample.Consequently, a lipophilic group nearly identical with that in Example12 was found. The fluoroplastic sheet thus treated was bonded to astainless steel plate with an epoxy resin-based adhesive and subjectedto a tensile shear test. The resultant adhesive strength was found to be140 kgf/cm².

EXAMPLE 18

2 g of aluminum hydroxide (Al(OH)₃) were dissolved in an aqueous 0.1 NNaOH solution. Following the same procedures as in Example 13, a spongesheet was soaked with the resultant solution, a transparentfluoroplastic (FEP) sheet sample was placed on the sponge sheet, and anArF laser beam (10 mJ/cm²) was irradiated from above. As a result,hydrophilicity similar to that in Example 13 was found. Thissurface-modified fluoroplastic sheet sample was bonded to a stainlesssteel plate with Aron Alpha (tradename), and the resultant adhesivestrength was found to be 60 kgf/cm².

EXAMPLE 19

A liquid of trimethoxyboron (B(OCH₃)₃) was placed in the reactor vessel56 illustrated in FIG. 6. Following the same procedures as in Example12, a fluoroplastic sheet sample was dipped in the solution, and an ArFlaser beam was irradiated on the interface between the solution and thesample. The result was that a contact angle nearly identical with thatin Example 12 was obtained. The fluoroplastic sheet thus treated wasbonded to a stainless steel plate with an epoxy resin-based adhesive andsubjected to a tensile shear test. The adhesive strength was found to be140 kgf/cm².

EXAMPLE 20

2 g of barium hydroxide (Ba(OH)₂) were dissolved in 50 cc of water, anda sponge sheet was soaked with the solution. A transparent fluoroplastic(FEP) sheet sample was placed on the sponge sheet, and an ArF laser beam(20 mJ/cm²) was irradiated from above. Consequently, hydrophilicityanalogous to that in Example 13 was found. When this surface-modifiedfluoroplastic sheet sample was bonded to a stainless steel plate withAron Alpha (tradename), the adhesive strength was found to be 30kgf/cm².

EXAMPLE 21

2 g of gallium acetate (Ga(CH₃ COO)₃) were dissolved in 50 cc of water,and a sponge sheet was soaked with the solution. A transparentfluoroplastic (FEP) sheet sample was placed on the sponge sheet, and anArF laser beam (20 mJ/cm²) was irradiated from above. Consequently,hydrophilicity analogous to that in Example 13 was found. When thissurface-modified fluoroplastic sheet sample was bonded to a stainlesssteel plate with Aron Alpha (tradename), the adhesive strength was foundto be 25 kgf/cm².

EXAMPLE 22

2 g of lithium acetate (LiCH₃ COO) were dissolved in 50 cc of methylalcohol, and a sponge sheet was soaked with the solution. A transparentfluoroplastic (FEP) sheet sample was placed on the sponge sheet, and anArF laser beam (20 mJ/cm²) was irradiated from above. Consequently,hydrophilicity analogous to that in Example 13 was found. When thissurface-modified fluoroplastic sheet sample was bonded to a stainlesssteel plate with Aron Alpha (tradename), the adhesive strength was foundto be 20 kgf/cm².

EXAMPLE 23

A sponge sheet was soaked with pure water (H₂ O), a transparentfluoroplastic (FEP) sheet sample was placed on the sponge sheet, and anArF laser beam (20 mJ/cm²) was irradiated from above. As a result,hydrophilicity similar to that in Example 13 was found. When thissurface-modified fluoroplastic sheet sample was bonded to a stainlesssteel plate with Aron Alpha (tradename), the adhesive strength was foundto be 20 kgf/cm². Note that almost identical results were obtained whenidentical experiments were done by using tap water in place of purewater.

EXAMPLE 24

A sponge sheet was soaked with formic acid (HCOOH), a transparentfluoroplastic (FEP) sheet sample was placed on the sponge sheet, and anArF laser beam (25 mJ/cm²) was irradiated from above. As a result,hydrophilicity similar to that in Example 13 was found. When thissurface-modified fluoroplastic sheet sample was bonded to a stainlesssteel plate with Aron Alpha (tradename), the adhesive strength was foundto be 25 kgf/cm².

EXAMPLE 25

A solution prepared by dissolving 2 g of tetrabenzyltitanium Ti(CH₂ C₆H₅)₄ in 50 cc of hexane (C₆ H₁₄) was placed in the reactor vessel 56shown in FIG. 6. Following the same procedures as in Example 12, afluoroplastic (FEP) sheet sample was dipped in the solution, and an ArFlaser beam was irradiated on the interface between the solution and thesample. Consequently, a lipophilic nature similar to that in Example 12was found. This surface-modified fluoroplastic sheet sample was bondedto a stainless steel plate with an epoxy resin-based adhesive andsubjected to a shear test. The resultant adhesive strength was found tobe 65 kgf/cm².

EXAMPLE 26

A sponge sheet was soaked with formic acid (HCOOH), and a transparentfluoroplastic (FEP) sheet sample was placed on the sponge sheet. A 100-Wlow-pressure mercury lamp beam which was condensed (to have a diameterof about 10 mm) by a reflecting mirror with a toroidal surface and alens was irradiated from above for 3 minutes. As a result,hydrophilicity analogous to that in Example 13 was found. When thissurface-modified fluoroplastic sheet sample was bonded to a stainlesssteel plate with Aron Alpha (tradename), the adhesive strength was foundto be 20 kgf/cm².

EXAMPLE 27

2 g of boric acid (H₃ BO₃) were dissolved in 50 cc of water. A thinliquid film of the resultant solution was kept in tight contact with amethacrylic resin (PMMA) sheet sample, and a KrF laser beam (20 mJ/cm²,100 shots) was irradiated on the resultant structure. Consequently, ahydroxyl group was substituted only in the exposed portion, and (OH) wasfound near 3300 cm⁻¹ as a result of ATR infrared spectroscopy.

EXAMPLE 28

2 g of amide sulfate (SO₂ (NH₂)₂) were dissolved in 50 cc of water. Athin liquid film of the resultant solution was kept in tight contactwith a methacrylic resin (PMMA) sheet sample, and a KrF laser beam (20mJ/cm², 300 shots) was irradiated on the resultant structure.Consequently, an amino group was substituted only in the exposedportion, and the contact angle with water was found to be 20°,indicating hydrophilicity.

EXAMPLE 29

2 g of sodium platinum (Na₂ Pt(OH)₆) were dissolved in 50 cc of water. Athin liquid film of the resultant solution was kept in tight contactwith a methacrylic resin (PMMA) sheet sample, and a KrF laser beam (20mJ/cm², 300 shots) was irradiated on the resultant structure.Consequently, a hydroxyl group was substituted only in the exposedportion, and the contact angle with water was found to be 20°,indicating hydrophilicity.

EXAMPLE 30

0.1 g of cyanogen bromide (CNBr) was dissolved in 10 cc of water. A thinliquid film of the resultant solution was kept in tight contact with amethacrylic resin (PMMA) sheet sample, and a KrF laser beam (20 mJ/cm²,300 shots) was irradiated on the resultant structure. As a consequence,a cyan group was substituted only in the exposed portion, and a peakindicating a triple bond of C and N was found near 2100 cm⁻¹ as a resultof ATR infrared spectroscopy.

EXAMPLE 31

2 g aluminum chloride (AlCl₃) were dissolved in 100-cc ethanol. A thinliquid film of the resultant solution was kept in tight contact with apolyethylene sheet sample, and an ArF laser beam (20 mJ/cm², 1000 shots)was irradiated on the resultant structure. Thereafter, the modifiedsurface was subjected to ESCA spectroscopy. The result was that a peakof Al was found at 71 ev, indicating that Al was substituted in thesample.

EXAMPLE 32

A thin liquid film of fluorocarbon 112 (CCl₂ FCCl₂ F) was kept in tightcontact with a polyethylene film sample, and an ArF laser beam (35mJ/cm², 500 shots) was irradiated on the resultant structure. As aresult, the contact angle with water was found to be 100° only in theexposed portion, demonstrating that the surface was converted intoteflon.

EXAMPLE 33

A thin liquid film of water (H₂ O) was kept in tight contact with apolyethylene film sample, and an ArF laser beam (25 mJ/cm², 3000 shots)was irradiated on the resultant structure. Consequently, the contactangle with water was found to be 15° only in the exposed portion,indicating that the surface was modified to be hydrophilic.

EXAMPLE 34

A thin liquid film of pure water (H₂ O) was kept in tight contact with apolyphenylenesulfide (PPS) film sample, and an ArF laser beam (12.5mJ/cm², 3000 shots) was irradiated on the resultant structure.Consequently, the contact angle with water was found to be 30° only inthe exposed portion, indicating that the surface was modified to behydrophilic.

EXAMPLE 35

A thin liquid film of pure water (H₂ O) was kept in tight contact with amethacrylic resin (PMMA) film sample, and an ArF laser beam (12.5mJ/cm², 9000 shots) was irradiated on the resultant structure.Consequently, the contact angle with water was found to be 40° only inthe exposed portion, indicating that the surface was modified to behydrophilic.

EXAMPLE 36

A thin liquid film of pure water (H₂ O) was kept in tight contact withan acrylonitrile butadiene styrene (ABS) film sample, and an ArF laserbeam (12.5 mJ/cm², 3000 shots) was irradiated on the resultantstructure. Consequently, the contact angle with water was found to be10° only in the exposed portion, indicating that the surface wasmodified to be hydrophilic.

EXAMPLE 37

A thin liquid film of pure water (H₂ O) was kept in tight contact with apolycarbonate resin film sample, and an ArF laser beam (12.5 mJ/cm²,3000 shots) was irradiated on the resultant structure. Consequently, thecontact angle with water was found to be 30° only in the exposedportion, indicating that the surface was modified to be hydrophilic.

EXAMPLE 38

A thin liquid film of pure water (H₂ O) was kept in tight contact with anylon.6 resin film sample, and an ArF laser beam (12.5 mJ/cm², 3000shots) was irradiated on the resultant structure. Consequently, thecontact angle with water was found to be 35° only in the exposedportion, indicating that the surface was modified to be hydrophilic.

EXAMPLE 39

A thin liquid film of pure water (H₂ O) was kept in tight contact with anylon.66 resin film sample, and an ArF laser beam (12.5 mJ/cm², 3000shots) was irradiated on the resultant structure. Consequently, thecontact angle with water was found to be 35° only in the exposedportion, indicating that the surface was modified to be hydrophilic.

EXAMPLE 40

A thin liquid film of formic acid (HCOOH) was kept in tight contact witha polyphenylenesulfide (PPS) film sample, and a KrF laser beam (12.5mJ/cm², 3000 shots) was irradiated on the resultant structure.Consequently, the contact angle with water was found to be 25° only inthe exposed portion, indicating that the surface was modified to behydrophilic.

EXAMPLE 41

A thin liquid film of formic acid (HCOOH) was kept in tight contact witha polyethylene film sample, and an ArF laser beam (12.5 mJ/cm², 3000shots) was irradiated on the resultant structure. Consequently, thecontact angle with water was found to be 35° only in the exposedportion, indicating that the surface was modified to be hydrophilic.

EXAMPLE 42

A thin liquid film of formic acid (HCOOH) was kept in tight contact withan acrylonitrile butadiene styrene resin (ABS) film sample, and a KrFlaser beam (12.5 mJ/cm², 2000 shots) was irradiated on the resultantstructure. Consequently, the contact angle with water was found to be 5°only in the exposed portion, indicating that the surface was modified tobe hydrophilic.

EXAMPLE 43

A thin liquid film of formic acid (HCOOH) was kept in tight contact witha polycarbonate resin film sample, and a KrF laser beam (12.5 mJ/cm²,2000 shots) was irradiated on the resultant structure. Consequently, thecontact angle with water was found to be 15° only in the exposedportion, indicating that the surface was modified to be hydrophilic.

EXAMPLE 44

A thin liquid film of formic acid (HCOOH) was kept in tight contact witha nylon.6 resin film sample, and a KrF laser beam (12.5 mJ/cm², 2000shots) was irradiated on the resultant structure. Consequently, thecontact angle with water was found to be 30° only in the exposedportion, indicating that the surface was modified to be hydrophilic.

EXAMPLE 45

A thin liquid film of formic acid (HCOOH) was kept in tight contact witha nylon.66 resin film sample, and a KrF laser beam (12.5 mJ/cm², 2000shots) was irradiated on the resultant structure. Consequently, thecontact angle with water was found to be 30° only in the exposedportion, indicating that the surface was modified to be hydrophilic.

EXAMPLE 46

2 g of ammonia fluoride (NH₄ F) were dissolved in 50 cc water. A thinliquid film of the resultant solution was kept in tight contact with apolyethylene film, and an ArF laser beam (12.5 mJ/cm², 3000 shots) wasirradiated on the resultant structure. As a result, an amino group wassubstituted only in the exposed portion, and the contact angle withwater was found to be 15°, indicating hydrophilicity.

EXAMPLE 47

A thin liquid film of formic acid (HCOOH) was kept in tight contact witha polyethylene film, and light of a 300-W Hg--Xe lamp was irradiated onthe resultant structure for 3 minutes. As a consequence, the contactangle with water was found to be 35° only in the exposed portion,demonstrating that the surface was modified to be hydrophilic.

EXAMPLE 48

A thin liquid film of formic acid (HCOOH) was kept in tight contact witha polyethylene film. Arc discharge (AC) of 9000 V was generated in a0.5-mm electrode gap in an N₂ atmosphere at 2 atm, and the emitted lightwas irradiated for 10 minutes. Consequently, the contact angle withwater was found to be 35°, demonstrating that the surface was modifiedto be hydrophilic.

EXAMPLE 49

A PTFE porous sheet with a thickness of 60 μm, a nominal pore size of0.1 μm, a porosity of 75%, and dimensions of 10 by 10 cm was dipped inmethanol and water in this order for 10 minutes each and then dipped inan aqueous compound solution for another 10 minutes, impregnating poreswith the aqueous compound solution. As the aqueous compound solution, anaqueous 4.1-wt % boric acid solution was used. In this aqueous solutionimpregnated state, an ArF laser was repeatedly irradiated at an energydensity of 200 mJ/cm² and a rate of 50 pulses/second for 120 seconds.The resultant material was washed with pure water and dried to obtain ahydrophilic fluoroplastic porous film.

When this film was dipped in pure water, the film rapidly absorbedwater.

The film was then subjected to surface analysis in accordance with ESCA(Electron Spectroscopy for Chemical Analysis). The result was that theO/C ratio, which was 0 before the treatment for impartinghydrophilicity, was improved to 0.18 after the treatment. In addition,the values of F/C before and after the treatment were found to be 2.0and 0.28, respectively, indicating that fluorine atoms were substitutedby hydrophilic groups. Waveform analysis was also made. Consequently,assuming the number of carbon atoms of a --CF₂ -- bond (292 ev) is 100,that of a --C--O-- bond (286 eV) was 63, and that of --C═O (288 eV) was11. This indicates the presence of hydrophilic functional groups. Nosuch functional groups were present before the treatment.

Even after the film was dipped in each of fluoric acid (50 wt %),hydrochloric acid (36 wt %), and sulfuric acid (97 wt %) at roomtemperature for 1 day, washed with water, and dried, the film maintainedits hydrophilicity. Also, the film maintained the hydrophilicity evenafter being washed with each of ethanol and acetone and dried.

The above hydrophilic fluoroplastic porous film was subjected to a waterpermeation test at a pressure difference of 235 mmHg, and the result wasthat the permeation flow rate of pure water was 3.5 cm³ /cm² /min. Thevalue of a film not subjected to the treatment of impartinghydrophilicity was 0, since the film did not get wet with pure water.The permeation flow rate of pure water measured after the film waswetted with ethanol was 3.5 cm³ /cm² /min. That is, no lowering wasfound in the permeation flow rate of the film after the treatment.

This hydrophilic fluoroplastic porous film was brought into contact withtetraethoxysilane, washed, and observed with an X-ray microanalyzer. Asa result, it was found that Si atoms were present in the pores of theporous body, indicating that the film was given hydrophilicity.

EXAMPLE 50

A laser was irradiated following the same procedures as in Example 49except that an aqueous 2 N lithium hydroxide solution was used as acompound solution. Even after being washed and dried, the resultant filmabsorbed water when dipped in pure water. Also, the film properties werenearly identical with those in Example 49.

EXAMPLE 51

A laser was irradiated following the same procedures as in Example 49except that an aqueous solution mixture of 1 N aluminum hydroxide and 1N sodium hydroxide was used as a compound solution. More specifically,the film impregnated with the solution was dipped in the solution, andan ArF laser was repeatedly irradiated at an energy density of 100mJ/cm² and a pulse rate of 50 pulses/second for 40 seconds. Even afterbeing washed and dried, the resultant film absorbed water when dipped inpure water. Also, the film properties were nearly identical with thosein Example 49.

EXAMPLE 52

A PTFE porous sheet with a thickness of 60 μm, a nominal pore size of0.1 μm, a porosity of 75%, and dimensions of 10 by 10 cm was dipped inmethanol and water in this order for 10 minutes each and then dipped inan aqueous compound solution for another 10 minutes, impregnating poreswith the aqueous compound solution. As the aqueous compound solution, anaqueous 4.1-wt % boric acid solution was used. In this aqueous solutionimpregnated state, a 50-W low-pressure mercury lamp was irradiated for60 seconds. The resultant material was washed with pure water and driedto obtain a hydrophilic fluoroplastic porous film.

When this film was dipped in pure water, the film rapidly absorbedwater.

The film was then subjected to surface analysis in accordance with ESCA(Electron Spectroscopy for Chemical Analysis). The result was that theO/C ratio, which was 0 before the treatment for impartinghydrophilicity, was improved to 0.18 after the treatment. In addition,the values of F/C before and after the treatment were found to be 2.0and 0.28, respectively, indicating that fluorine atoms were substitutedby hydrophilic groups. Waveform analysis was also conducted.Consequently, assuming the number of carbon atoms of a --CF₂ -- bond(292 ev) is 100, that of a --C--O-- bond (286 eV) was 81, and that of--C═O (288 eV) was 18. This indicates the presence of hydrophilicfunctional groups. No such functional groups were present before thetreatment.

Even after the film was dipped in each of fluoric acid (50 wt %),hydrochloric acid (36 wt %), and sulfuric acid (97 wt %) at roomtemperature for 1 day, washed with water, and dried, the film maintainedits hydrophilicity. Also, the film maintained the hydrophilicity evenafter being washed with each of ethanol and acetone and dried.

The above hydrophilic fluoroplastic porous film was subjected to a waterpermeation test at a pressure difference of 235 mmHg, and the result wasthat the permeation flow rate of pure water was 3.7 cm³ /cm² /min. Thevalue of a film not subjected to the treatment of impartinghydrophilicity was 0, since the film did not get wet with pure water.The permeation flow rate of pure water measured after the film waswetted with ethanol was 3.7 cm³ /cm² /min. That is, no lowering wasfound in the permeation flow rate of the film after the treatment.

This hydrophilic fluoroplastic porous film was brought into contact withtetraethoxysilane, washed, and observed with an X-ray microanalyzer. Asa result, it was found that Si atoms were present in the pores of theporous body, indicating that the film was given hydrophilicity.

EXAMPLE 53

Ultraviolet radiation was irradiated using a low-pressure mercury lampfollowing the same procedures as in Example 52 except that an aqueous 2N lithium hydroxide solution was used. Even after being washed anddried, the resultant film absorbed water when dipped in pure water.Also, the film properties were nearly identical with those in Example52.

EXAMPLE 54

Ultraviolet radiation was irradiated using a low-pressure mercury lampfollowing the same procedures as in Example 52 except that an aqueoussolution mixture of 1 N aluminum hydroxide and 1 N sodium hydroxide wasused as a compound in solution. More specifically, the film impregnatedwith the solution was dipped in the solution, and ultraviolet radiationwas irradiated by using a 100-W low-pressure mercury lamp or a 2-kWhigh-pressure mercury lamp. Even after being washed and dried, theresultant film absorbed water when dipped in pure water. Also, the filmproperties were nearly identical with those in Example 52.

EXAMPLE 55

A nonporous PTFE film (Nitoflon Tape No. 900 (tradename) 38 μm thick,manufactured by NITTO DENKO CORP.) was irradiated with ultravioletradiation in the same compound solution as in Example 51. The contactangle with pure water of the resultant film was found to be 55°,indicating that the film was modified to be hydrophilic. The angle was120° before the treatment.

A double-sided adhesive tape (No. 500 manufactured by NITTO DENKO CORP.)was adhered to the hydrophilic surface of the film at the contact sidewith the solution. The adhesive strength (JIS Z 0237) as measured by a180° peel-back method was found to be 13 times as large as that beforethe irradiation.

Industrial Applicability

In the present invention, dehydrogenation, defluorination, orsubstitution with various functional groups or metal atoms isselectively performed only for an exposed portion of a solid material tobe treated (e.g., a fluoroplastic, a synthetic resin such as a plasticmaterial having a C--H bond, glass, a metal, an animal or a plant, or aceramic). Consequently, optical modification is performed to give thatportion hydrophilicity, adhesion properties, ink absorptivity, corrosionresistance, and conductivity resulting from metal substitution. As anexample, a fluoroplastic material can be bonded to a material of thesame type or a different type with an extremely high adhesive strengthwith no damage to the original characteristics of the fluoroplasticmaterial. This makes it possible to provide a fluoroplastic materialcomposite structure with a high chemical resistance or the like bybonding a fluoroplastic sheet to the surface of, e.g., an epoxy resin,bakelite, an ABS resin, concrete, or a metal. In addition, by modifyinga porous fluoroplastic material to have hydrophilicity, it is possibleto use the material as a filtration device, such as a cartridge filter,a plate-type module supported by a plate and a frame in a plane filmstate, or a hollow fiber film module, a separator of a cell, or aheat-resistant adhesive tape.

As has been discussed above, the present invention can be applied to awide variety of uses, such as the wall surfaces of vessels in chemicalplants required to have a high mechanical strength, chemical laservessels, high-voltage instruments, and printed circuit boards, in thechemical, machine, electronic parts, and gas/power industries.

What is claimed is:
 1. A method of photochemically modifying a solidsurface of a fluoroplastic material, comprising;providing a liquidcontaining a chemical species selected from (a) a liquid compound and(b) a solution of a compound in a solvent; containing said liquid withsaid surface and a window member to form a layer of said liquid, saidwindow member being substantially transparent to ultraviolet, visible orinfrared radiation and positioned in relation to the fluoroplasticmaterial such that capillary force is exerted upon the layer of saidliquid to form and maintain an interface between the liquid and saidsurface, and applying said radiation through the window member onto theinterface to effect a reaction of the chemical species with, and thusmodify the surface of, the fluoroplastic material by liberatingfluorine.
 2. A method of photochemically modifying a solid surface of afluoroplastic material, comprising;forming a layer of a liquid substancecontaining a chemical species selected from the group consisting of (a)a liquid compound and (b) a solution of a compound in a solvent, betweena window member and said fluoroplastic material, said window memberbeing transparent to ultraviolet radiation and positioned closely enoughto said fluoroplastic material such that capillary action is exertedbetween said window member and said fluoroplastic material to form saidlayer of the liquid substance; and irradiating said ultravioletradiation in an amount sufficient to liberate fluorine from saidfluoroplastic material through said window member on an interfacebetween the surface of said fluoroplastic material and said liquidsubstance, thereby effecting a reaction of said chemical species withthe surface of said fluoroplastic material to modify the surface of saidfluoroplastic material.
 3. A method according to claim 2, wherein saidliquid substance is said liquid compound which is selected from thegroup consisting of water, an alcohol, petroleum, an aromatic compound,silicone oil, trichloroethylene, hydrogen peroxide, HCl, H₂ SO₄, HCOOH,(COOH)₂, CH₃ COOH, NH₃, N₂ H₄ and NH₄ F.
 4. A method according to claim2, wherein said liquid substance is the solution, and the solvent isselected from the group consisting of water, ammonia, a halogencompound, an alcohol, a phenol, an organic acid, a nitrile, a nitrocompound, an amine and a sulfur compound.
 5. A method according to claim2, wherein said window member is formed of a material selected from thegroup consisting of ultraviolet-transmitting glass, rock crystal,sapphire, diamond, TiO₂, Ge, Si, barium fluoride, magnesium fluoride,calcium carbonate, lithium fluoride, calcium fluoride, a fluoroplasticmaterial, an acrylic resin, a styrene resin and a carbonate resin.
 6. Amethod according to claim 2, wherein said ultraviolet radiation isirradiated from a source selected from the group consisting of anexcimer laser, an Ar⁺ laser, Kr⁺ laser, an N₂ laser, a harmonicsultraviolet laser obtained by a nonlinear material, and an ultravioletlamp operating by an arc, corona or silent discharge.